During surgery, retractors, such as those found in the BOOKWALTER™ retractor kit, which is commercially available from Codman & Shurtleff, Inc. of Raynham, Mass., are often used to assist the surgeon and other operating room personnel to provide exposure to the surgical site for a broad range of surgical procedures. In surgical operations of the chest or abdomen, for example, it is often necessary to use a retraction apparatus to retain tissue away from the operative site. Typically, the refraction apparatus includes a housing member configured to lock onto a circumferential ring 10 located above the operative site (see FIG. 1). To maintain ring 10 in a fixed position, ring 10 can be connected to a support post 12 adjacent to the site by a horizontal bar 14 that has a flexible joint 16 (horizontal flex bar) to permit ring 10 to be oriented in various positions, as shown in FIG. 1. A horizontal extension arm may also be attached to the support post for supporting the circumferential ring. Within the housing member a refraction blade can usually be found for grabbing the tissue around the surgical incision. The housing member can also include a ratcheting mechanism and/or a tilting mechanism to draw the retraction blade away from the incision, thereby effecting the pulling away and/or lifting of the tissue around the incision to expose the desired surgical area. Examples of such retractor systems are disclosed in U.S. Pat. Nos. 4,254,763, 4,424,724, 5,375,481 and 6,808,493, the disclosures of which are hereby incorporated by reference in their entirety. During open surgical operations, such as, for example, open bariatric, ALIF procedures, hepatic resections, transplant procedures, abdominal aortic aneurysms, hernia repair, appendectomy and others, many different instruments are used, such as, for example, a retractor blade with ring attachment systems are used. In some medical procedures, different size rings are required to accommodate different procedures, different size patients, different doctor preference, etc. In addition, in some medical procedures, the doctor may want to separate the ring so that one half ring is in one plane and the other half ring is spaced from and in a different plane from the other half ring.
Thus, despite these refraction systems, there continues to be a need for a retraction system that can securely hold a retractor ring while permitting the size of the ring to vary.